The present application claims priority to Japanese Application No. P11-314290 filed Nov. 4, 1999, which application is incorporated herein by reference to the extent permitted by law.
1. Field of the Invention
The present invention relates to a magnetic head for performing recording to and reproduction from a high coercive force magnetic recording medium such as a so-called metal evaporated tape or the like.
2. Description of the Related Art
Recently, a signal has come to be recorded in a high density in a field of magnetic recording. For realizing the high density recording, there a magnetic recording medium having a high coercive force and a high residual magnetic flux density such as the so-called metal evaporated tape made by affixing a ferromagnetic metal material on a non-magnetic base directly has been in practical use.
With the change of the magnetic recording medium, a core material of a magnetic head is demanded to have a high saturation magnetic flux density and a high permeability.
For meeting such a demand, there has conventionally been proposed a so-called metal-in-gap (MIG) type magnetic head using ferrite as an auxiliary core material and forming metal magnetic thin films having a high saturation magnetic flux density on the ferrite as main core materials for forming the gap portion thereof with the metal magnetic thin films. The MIG type magnetic head is suitable for recording to and reproduction from the metal evaporated tape.
Incidentally, because there is a demand for such a kind of the magnetic head to perform well its recording and reproducing operations to a magnetic recording medium having a high coercive force such as the above described metal evaporated tape as the change of the recording density to be higher has remarkably progressed in recent years, there is sought a metal magnetic material that has a higher saturation magnetic flux density for ensuring a sufficient recording magnetic field and that has a superior soft magnetic characteristic even in a high frequency region.
In such a situation, because a fine crystal metal soft magnetic thin film, the main component of which is Fe, has a high saturation magnetic flux density and exhibits a superior soft magnetic characteristic, the fine crystal metal soft magnetic thin film begins to be put into practical use in place of the conventional metal magnetic material for a magnetic head.
However, because the above described Fe-base fine crystal metal soft magnetic thin film has a structure that almost all of the volume of the thin film is occupied by a fine crystal having a composition near to pure iron, the thin film has a problem that the corrosion resistance thereof is generally low and thereby the reliability of a device using the film is lowered.
Furthermore, the soft magnetic characteristic of the MIG type magnetic head using the Fe-base fine crystal metal soft magnetic thin film in a direction parallel to the surface of the film is superior, but the soft magnetic characteristic thereof in the thickness direction of the film is inferior. That is, the permeability thereof in the thickness direction of the film becomes lowered, and thereby the whole soft magnetic characteristic of the Fe-base fine crystal metal soft magnetic thin film is lowered. In other words, the intrinsic reproducing characteristic of the MIG type magnetic head using the Fe-base fine crystal metallic soft magnetic thin film is not brought into full play.
Accordingly, the present invention is proposed on the basis of the actual circumstances of the prior art, and aims to provide a magnetic head having a high saturation magnetic flux density and superior in the corrosion resistance, and further having a superior soft magnetic characteristic and a reproducing characteristic.
For attaining the aforesaid object, according to an aspect of the present invention there is provided a magnetic head a magnetic core of which forms a closed magnetic circuit and which has a gap in the closed magnetic circuit, wherein: at least a part of the magnetic core is composed of a soft magnetic laminated film made by laminating a soft magnetic thin film layer and a noble metal layer, and the soft magnetic thin film layer is exhibited by a composition formula of FeaSibTacRudGaeNf (where xe2x80x9caxe2x80x9d, xe2x80x9cbxe2x80x9d, xe2x80x9ccxe2x80x9d, xe2x80x9cdxe2x80x9d, xe2x80x9cexe2x80x9d and xe2x80x9cfxe2x80x9d in the formula indicate compositions of respective elements by the atomic percent), and ranges of the compositions are:
62 atomic percent less than a less than 75 atomic percent;
7 atomic percent less than b less than 18 atomic percent;
3 atomic percent less than c less than 10 atomic percent;
0 atomic percentxe2x89xa6d less than 10 atomic percent;
0 atomic percentxe2x89xa6e less than 6 atomic percent;
5 atomic percent less than f less than 12 atomic percent; and
b+c greater than 13 atomic percent, and the noble metal layer contains at least a kind of Pt, Au, Ag and Pd.
Because, in the thus constructed magnetic head, the soft magnetic thin film layer is a fine crystal deposition type soft magnetic thin film, the high saturation magnetic flux density and the superior soft magnetic characteristic are realized. And further, because a part which constitutes a core is replaced by a Fexe2x80x94Ruxe2x80x94Gaxe2x80x94Si alloy, a superior corrosion resistance performance can also be realized. In addition, because the soft magnetic laminated film is made by laminating the soft magnetic thin film layer and the noble metal layer, an xcex1-Fe (110) orientation is produced after heat treatment. Consequently, a superior soft magnetic characteristic is realized together with a great improvement of the permeability in the film thickness direction thereof.